The present invention relates to a lamp comprising at least one OLED lighting means lying flat on an at least partially light-transmissive carrier plate and formed as an OLED panel, wherein at least two contact shoes respectively assigned to an OLED panel are attached onto the rear side of the carrier plate that is facing away from the light-emitting side, and respectively comprise means for contacting one pole each of the OLED panel, and wherein at least one contact shoe has an attachment device, by means of which the OLED panel is attached onto the carrier plate; the attachment device is preferably a clamping device, by means of which the OLED panel is attached in a clamped manner.
Organic LEDs, in what follows designated as OLEDs, have already been of known art for a number of years, and thus far have been predominantly deployed in the display sector. The reason for this lies in the fact that until quite recently the luminous flux outputted by the OLEDs has not been sufficient for general lighting purposes. It has therefore only been possible to deploy OLEDs for supplementary lighting or effect lighting. Moreover, until quite recently the manufacturing costs of the OLEDs were so high that any deployment for general lighting purposes was not economical. In recent times however, ever more effective OLEDs with increasing light output have been developed, and the production costs have steadily reduced.
For example, the company Philips offers two-dimensional OLED panels under the designation “lumiblade GL 350” which, with a size of 124.5×124.5 mm, deliver a luminous flux of 120 lumens of white light, which for example is perfectly sufficient for a table lamp or other applications in the field of living room lighting (see the publication on the Internet under http://www.lighting.philips.de/lightcommunity/trends/oled/lumibladeoledgl350.wpd.)
In the case of OLED panels of the type cited the actual OLED stack is, as a general rule, located on a carrier plate of glass or plastic. If the aim is to integrate such an OLED panel into a lamp, in principle a design solution comes into consideration in which the OLED panel, or a plurality of such OLED panels, is fitted onto a light-transmissive carrier plate. However, here there are still a number of technical problems to be solved, namely on the one hand contacts must be made with the OLED panel in order to supply the latter with power, and on the other hand, the OLEDs must be securely attached onto the carrier plate. Finally, light technology measures are on occasion required, which ensure an effective coupling-out of the light of the light emitted by the OLEDs, and a uniform light distribution over the light-radiating area of the carrier plate.
From DE 10 2010 038 251 A1 an OLED lighting means in the form of an OLED panel has become of known art, together with a lamp that has a plurality of the said OLED panels in a matrix-type arrangement with rows and columns. A plurality of contacts is assigned to each of the OLED lighting means to provide the electrical contacts for the respective lighting means. The lamp has a housing with a frame, which borders the edges of the OLED panel on the front side, and with a housing rear wall, in which the contacts are also held. The housing rear wall consists of a plastic that is not light transmissive, since the intention is for light emission to take place only on the front side via the illuminated area bordered by the frame. Moreover, on the rear side of the housing rear wall a socket is fitted, via which the lamp can be connected to supply cables. In the case of the said lamp of known art the OLED panel is thus located between the front side frame and the rear wall that is not light transmissive. Since each OLED panel on the light emission side has a frame bordering its illuminated area, in a matrix-type arrangement of a plurality of such lighting means the whole light-emitting surface of the lamp is interrupted by the respective webs between the rows and columns of the frame of the lighting means. While it is true that a total illuminated area is created, in that a plurality of lighting means of the same type are arranged next to one another, each lighting means remains a separate unit, and there is no common carrier plate on which the plurality of lighting means are located.
In DE 10 2011 077 687 A1, a module (a lamp) is described with a plurality of OLED panels arranged in the form of a matrix in a plurality of rows, in which a contact structure is arranged centrally between two OLED panels located next to one another. The OLED panels can be eight-sided or four-sided in outline. Contact regions along facing edges of adjacent OLED panels can be connected in an electrically conducting manner via a spring of the central contact structure. Each OLED panel has its own substrate, which serves as a carrier for the first electrode layer, and the sequence of organic layers with the emitter layer and the second electrode layer, wherein in professional circles the said sequence of layers is generally designated as an OLED stack. The functional layers of each OLED panel are covered on their upper side by a glass plate serving to provide encapsulation. The said encapsulated surface on the upper side is that surface of the OLED panel from which light emission takes place. If one thus views the substrate as a carrier plate for the individual OLED panel, then the said carrier plate is located on the rear side of the OLED panel, which is located opposite to the side emitting the light. Even in the case of OLED panels that are closely adjacent, moreover, the carrier plates of the OLED panels are separate from one another, since each OLED panel takes the form of an autonomous unit, which represents a lighting means for the lamp. If a plurality of rectangular OLED panels are arranged next to one another in rows in the form of a matrix, a base frame is on the one hand provided with recesses as additional mechanical holding devices, and a top frame is arranged on the base frame, and mechanically connected with the latter. The top frame has cruciform webs, which cover the contact structures located centrally between the adjacent OLED panels. In overall terms, a light emission surface is thus created, which is subdivided by the webs of the base frame and top frame in the longitudinal and transverse directions. In the variants described in the said document, in which eight-sided OLED panel modules are arranged in rows, the latter are connected with one another in their edge regions by means of, for example, rod-shaped connecting elements and eyelets. Thus here no common carrier plate is provided, on which a plurality of OLED panels is fitted, and which serves as a supporting structure for the latter.
In US 2013/0076229 A1 a two-dimensional panel-type OLED lighting means module is described, together with a lamp comprising the said OLED lighting means module. In addition to the actual light-emitting module with the OLED layers, the OLED lighting means comprises a multi-part attachment part. In front of the OLED panel a transparent covering is located on the light-emitting side, while on the rear side is located a housing made of a non-transparent material, which also holds the front side cover. The closed housing prevents any light emission from the rear side of the module. The light-emitting module is bordered by a comparatively wide rectangular frame, which reduces the light-emitting area. The contacts with the OLED stack are also made via the frame. In the said OLED lighting means module measures are taken in order to deflect light emitted from the light-emitting module into the transparent covering in its edge region, by means of scattering or reflection, back into the transparent plate, so as to achieve a certain illumination also in the edge region by this means. While it is true that here a loss of light as a result of total reflection in the projecting edge region of the transparent plate is prevented, the effective surface area of that part of the OLED that is emitting light with sufficient luminous intensity remains the same. In the document no technical solution is described as to how one, if required, combines a plurality of the said OLED lighting means modules with one another to form a lamp. Since the lighting means modules have comparatively wide peripheral edges, one would not achieve any continuous illuminated area by arranging them in rows. If one were to view the lower transparent covering of the OLED lighting means module as a carrier plate for the module, the said carrier plate would be assigned only to a single lighting means, wherein the side walls of the rear side housing significantly overlap the carrier plate. In this solution of known art a continuous carrier plate for a plurality of lighting means modules is neither provided, nor is possible in any technically logical manner.
From DE 10 2006 054 584 A1 an item of storage furniture is of known art, with a storage surface that comprises a two-dimensionally shaped radiation-emitting component in the form of a plate-form OLED. Fundamentally, therefore, from this document it is of known art to illuminate two-dimensional plate-form regions of an item of furniture by means of OLED panels. However, the said document contains no statements as to how one places a plurality of OLED panels into a storage surface. Since at the present time the largest OLED panels of the latest generation that can be obtained commercially have a size of 120 mm×120 mm, with the use of only one OLED it is only possible to illuminate a comparatively small storage surface of an item of furniture.
In DE 10 2004 026 730 A1 it is proposed to illuminate flexible film-type surfaces with the aid of LEDs, or also OLEDs. Here, for example, a transparent film is suspended in a frame system. Point-form light-emitting diodes are respectively introduced into the film, spaced apart from one another in a matrix-type arrangement, wherein the contacts are made by means of wires, running horizontally and vertically, that cross each other. With such an arrangement one does not obtain uniform two-dimensional light radiation, but rather the impression of multiple points of light. In the said document the examples do not contain any forms of embodiment by means of which a plurality of two-dimensional OLED panels are combined with one another so as to create a uniform illuminated area.
DE 10 2011 079 014 A1 describes lighting modules in the form of two-dimensional OLED panels. In the said document, it is also stated that one can create a two-dimensional illumination arrangement from a plurality of such lighting modules, wherein the individual lighting modules are electrically connected with one another via electrical connections, either in series or in parallel. Here the OLED panel has a structure with an active element, which contains the light-emitting OLED stack, and is held in the form of a sandwich between two plates, namely a carrier plate and a plate serving to provide encapsulation. Both the carrier plate, and also the encapsulation substrate can consist of a light-transmissive material, for example, glass or plastic. In this document the fundamental problem of conventional OLED panels has been recognised, namely that these have a frame bordering the light-emitting surface, as a result of which the surface area of effective light emission is restricted. In order to be able to design a narrower frame it is proposed to arrange the conducting tracks, which form the electrical connections for making contact with the OLEDs, externally on the periphery on the end faces of the panel. With the narrower frames the proportion of non-illuminating surfaces and intermediate spaces between the panels in a combination of a plurality of OLED panels is indeed reduced, but the fundamental problem of interruptions caused by non-illuminating strips remains. The said document does not disclose any practical solution as to how, by combining a plurality of OLED panels, a continuous illuminated area is created in a lamp. Just an individual OLED panel is shown in each case, which represents only one “lighting means”. Even if the individual lighting means here has a transparent carrier plate, this carrier plate is only assigned to the said lighting means, with the encapsulation plate connected securely to a non-detachable unit. If one were to release the connection between carrier plate and encapsulation plate of such an OLED panel, the active OLED layer would be exposed to the atmosphere, and would be impaired in its function and service life by moisture and atmospheric oxygen. The individual OLED panel with the sandwich-type arrangement of two plates, which surround the active light-emitting layer, is thus an autonomous unit that cannot be disassembled, a fact that the designer of a lamp, in which such OLED panels are used as lighting means, must take into consideration. If one thus uses a plurality of OLED panels of this type in a lamp, each OLED panel has its own carrier plate, wherein the total material thickness of a commercial OLED panel with a sandwich-type construction of the type cited above is, for example, approx. 1.8 mm.
In DE 10 2006 015 437 A1 a lighting tile is described, which has at least one OLED as a lighting means. The lighting tile has a layered construction with a carrier plate on its rear side, a visual effect plate on its front side, via which the light is emitted, and an intermediate space between the two plates, which accommodates the OLED layers, and is sealed against the environment. Furthermore, an electrical connection is provided on the rear side of the lighting tile in order to make contact with the OLED. While it is stated in the document that in principle a plurality of OLEDs can be used in one lighting tile, no practical technical solution is shown as to how this idea is implemented. The carrier plate on which the OLED layers are fitted is here the rear-side non-transparent plate of the lighting tile. If one were to arrange a plurality of such lighting tiles next to one another, the result would once again be non-illuminated surfaces between the tiles, since here too the effective light-emitting surface area is smaller by some margin than the surface area of the lighting tile in total.
A further OLED lighting means is described in DE 10 2011 107 642 A1. This has a visible side carrier plate made of glass, via the surface of which the light is emitted. The OLED layers are fitted onto the rear side of the carrier plate, wherein a cover plate is located behind the carrier plate, such that the OLED layers lie between carrier plate and cover plate. Furthermore, a plate-form cooling body is located behind the carrier plate, via which cooling body the heat is to be removed. The whole arrangement is surrounded by a housing of an insulating material, in which are also held angled contacts with two arms, of which one arm makes contact with a metallic layer in the edge region of the carrier plate. By virtue of the non-transparent cooling body light emission is only possible on one side. The insulating material body forms a comparatively wide frame, which surrounds the light-emitting surface of the OLED lighting means peripherally on all sides, so that in the event of a combination of a plurality of OLED lighting means of this type no continuous illuminated area can be created. This document also does not give any suggestion as to how to create a lamp using a plurality of OLED lighting means of this type. Here a solution is just presented for mounting and making contact with a carrier plate layered with an OLED stack. The result of this is once more an individual OLED lighting means, wherein here an individual solution for a further OLED lighting means is described.
However, in the marketplace there are OLED panels of known art of a small number of leading suppliers of lighting means, which have prescribed design features for contacts, mounting, etc., such that it is advantageous for the lamp designer, when designing a lamp on the basis of OLED lighting means, to take into consideration the subject matter of these commercially available OLED lighting means, instead of generating a further individual OLED lighting means.